The research objective is to quantitate the relationship between precursor fatty acid composition in endogenous tissue lipids and potential prostaglandin (PG) production ex vivo. PGF2alpha, E2, E1, 6-keto-F1alpha and thromboxane (TX) B2 are measured by radioimmunoassay. Fatty acid composition is altered by feeding fats with varying poly-unsaturated and saturated fatty acid (P/S) ratios. These alterations can then be correlated with the known involvement of PG in platelet aggregation, pulmonary resistance, hypertension, lipolysis and immunity. The ranking of PG produced by norepinephrine stiumlated adipocytes was 6-keto-PGF1 (spontaneous degradation product of PGI2), PGE1, PGF2alpha, then TXB2 (spontaneous degradation product of TXA2). Release of all PG except TX increased linearly as the dietary P/S ratio was raised from 0.0 to 3.0. In a follow-up study, measurement of serum PG concentration which reflects primarily PG released by platelets showed no alterations associated with dietary P/S ratio. The differences in design between the experiment reported last year and the one reported this year were fed vs fasted, feeding for 2 months vs 6 months, and female vs male, respectively. In collaboration with other projects, it was clearly shown that supplemental dietary vitamen E depresses PG production and dietary selenium has no effect. Radioimmunoassays of the circulating metabolites of PGF2alpha and E2 are being developed and validated. The effect of composition of diet on "total" body PG production can then be measured.